Rotary centrifugal speed-responsive control device

ABSTRACT

A control-actuating centrifugal speed-responsive device for mounting on the shaft or other rotatable member of the device whose speed is to be monitored or controlled. The device includes a disk-shaped conical spring, preferably of the snap-action type, which is loosely retained or supported in the body of the device so as to have knife-edge pivotal movement in its operative sequence. Circumferentially spaced weights are secured to the peripheral portion of the spring to actuate the spring in response to centrifugal forces and cause retraction of a controlengaging shoe which is operatively secured to the spring and normally projected or extended by the spring in the static position of the device to either engage or disengage from the control being actuated. Recesses are provided in the body of the device for containing the weights for the purpose of limiting excessive excursion of the weights resulting from the centrifugal forces to which they are subjected. A stabilizer member or plate is secured to the shoe in position to underlie the spring and provide a stabilizing support for the spring when the shoe is in its spring-urged projected position. The axial spacing between the shoe and the stabilizer member is predetermined to effect pretensioning of the spring when it is in the static position, so that increased stability of the spring is achieved and operating characteristics of the device can be established with greater precision.

United States Patent [191 Greenhut Feb. 26, 1974 l l ROTARY CENTRIFUGAL SPEED-RESPONSIVE CONTROL DEVICE [76] Inventor: Joseph Greenhut, 3333 Warrenville Center Rd., Shaker Heights, Ohio 44122 22 Filed: Sept. 11, 1972 [21] Appl. No.: 287,755

Primary Examiner.lames J. Gill Attorney, Agent, or Firm-Isler & Ornstein [57] ABSTRACT A control-actuating centrifugal speed-responsive device for mounting on the shaft or other rotatable member of the device whose speed is to be monitored or controlled. The device includes a disk-shaped conical spring, preferably of the snap-action type, which is loosely retained or supported in the body of the device so as to have knife-edge pivotal movement in its operative sequence. Circumferentially spaced weights are secured to the peripheral portion of the spring to actuate the spring in response to centrifugal forces and cause retraction of a control-engaging shoe which is operatively secured to the spring and normally projected or extended by the spring in the static position of the device to either engage or disengage from the control being actuated. Recesses are provided in the body of the device for containing the weights for the purpose of limiting excessive excursion of the weights resulting from the centrifugal forces to which they are subjected. A stabilizer member or plate is secured to the shoe in position to underlie the spring and provide a stabilizing support for the spring when the shoe is in its spring-urged projected position. The axial spacing between the shoe and the stabilizer member is predetermined to effect pretensioning of the spring when it is in the static position, so that increased stability of the spring is achieved and operating characteristics of the device can be established with greater precision.

17 Claims, 7 Drawing Figures ROTARY CENTRIFUGAL SPEED-RESPONSIVE CONTROL DEVICE BACKGROUND OF THE INVENTION gally-actuated weights on the device cause retraction of an axially movable portion of the device away from the stationary switch, permitting it to open the starting winding when a desired cut off speed has been attained. The general structure and operation of such a centrifugal speed-responsive device is disclosed in my US. Pat. No. 2,6 1 6,682 to which reference is made for a detailed explanation of the then state of the art.

Although the most extensive use of this type of spring-loaded centrifugal speed-responsive device is in connection with the aforesaid electrical motor control,

such devices have a broader range of utility in the speed-sensing or speed control of a wide range of mechanisms, some of which are in themselves rotary mechanisms, and others of which are driven by electrical motors or other rotary prime movers.

The type of centrifugal speed-responsive device disclosed in my aforesaid US. Pat. No. 2,616,682 permitted the shoe or spool of the device to be projected to the full extent of the spring, so that the shoe had a tendency to wobble and tilt or cock as a consequence of the extreme flexibility of position permitted by the prior art design. This high degree of flexibility in the posture of the shoe when it was engaging the stationary switch arm, caused an undesirable and unnecessarily high degree of fatigue in the fingers of the conical disk spring utilized in the speed-responsive device, causing accelerated and premature failure of the spring.

Furthermore, the flux density of the electrical motors on which such devices are predominantly used, tends to set up a vibration in the disk spring which further contributes to excessive fatigue on the fingers of the conical spring and premature fracture or failure. The magnetic effect of the flux density on the centrifugal weights also causes them to vibrate resulting in weakening and loosening at the point of rivet connections to the spring, thus further contributing to spring fatigue at these points. This vibration of the weights also causes some excessive wear of the damping grommets which are mounted on the centrifugal weights and which serve as the fulcrum for their outboard movement. These same disadvantageous effects on the grommet and on the rivet connections also are created by the inertial resistance of the centrifugal weights to rapid acceleration of orbital movement which causes the weights to be displaced orbitally in a direction transverse to the desired outboard movement of the weights resulting from pure centrifugal force.

The foregoing fatigue problems on the disk spring and the problems of excessive wear on the damping grommets have been magnified in recent years by the development of electrical motors having very high magnetic flux density and reduced shaft size and mass, with greater rates of speed acceleration, all of which combine to increase the magnetic and vibrational problems above recited and cause an even greater and more destructive effect on the mechanical parts of the centrifugal speed-responsive device. Another factor which has resulted in excessive fatigue of the disk spring and excessive wear on the damping grommets has been excessive excursion of the weights in their centrifugallyinduced outboard positions after the cut-out speed has been attained and the shoe of the centrifugal device has been retracted, but the rotary unit is still accelerating to maximum operating or running speed.

SUMMARY OF THE INVENTION It is the primary object of the invention to provide an improved centrifugal speed-responsive device in which the shoe and spring have increased stability and are less subject to the effects of vibrational fatigue.

Another object of the invention is to provide such an improved device in which the weights are mechanically retained against excessive excursion.

It is a further object of the invention to provide an improved pivotal support for the conical disk spring utilized in the device.

Still another object of the invention is to provide such a device with a more stable spool operating characteristic so as to permit reduction in the mass and size of the device while still maintaining improved and more precise operating characteristics and compatability with use in smaller motor frames.

Still another object of the invention is to provide such a device having cooling fan blades or vanes integrated therewith, so as to eliminate the need for a separate fan element.

Still another object of the invention is to provide a device of the character described which can be assembled to narrower operating tolerances to achieve and establish more predictable and more precise operating characteristics.

Other objects and advantages of the invention will become apparent during the course of the following description.

BRIEF DESCRIPTION OF THE DRAWING In the drawings, in which like reference numerals designate like parts throughout the same,

FIG. 1 is a view in side elevation of a centrifugal speed-responsive device embodying the features of my invention illustrating the manner in which it might be utilized in an electric motor, the projected or extended position of the shoe of the device being shown in solid lines and the retracted position being shown in phantom outline.

FIG. 2 is an enlarged cross-sectional view, taken as indicated on line 2-2 of FIG. 1, and showing a plan view of the device with portions thereof broken away to show details of the invention.

FIG. 3 is an enlarged cross-sectional view, taken as indicated on line 3-3 of FIG. 1, and showing a plan view of the opposite face of the device.

FIG. 4 is a view similar to FIG. 3, but with the body portion of the device removed.

FIG. 5 is a fragmentary cross-sectional view, taken as indicated on line 5-5 of FIG. 2, and showing in phantom outline the manner in which the excessive excurweights and a separate retainer means for limiting separation of the disk from the body.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring more particularly to FIGS. 1-7 of the drawings, a centrifugal speed-responsive control device is shown in FIG. 1 of the drawings in the environment of an electric motor 11, by way of example. The device 10 is mounted for rotation coaxially with the shaft 12 of the electric motor and is positioned so that its axially movable control-actuating spool or pad or shoe 13 engages and closes the switch arm 14 of a stationary switch 15 which is mounted in the end bell of the motor. As is well known to those familiar with the art, the stationary switch 15 is an element of the starting winding circuit of the motor and this circuit is maintained closed in the static condition of the motor or when it is initially starting up and has not yet reached cut-out speed.

As indicated in phantom outline in FIG. 1, when the motor is electrically energized and attains cut-out speed, the centrifugal weights 16 of the device 10 are caused to pivot outwardly due to centrifugal forces. This movement of the weights is translated into an axial retraction of the shoe 13, withdrawing it from its engagement with the switch arm 14 and permitting the switch arm to spring open, thus taking the starting winding out of the circuit. The energized motor continues to run at its operating speed on the running winding 11, as is well known in the art. The cut-out speed is predetermined in the design and calibration of the device 10 in relation to the centrifugal forces involved, the forces of the stationary switch and the speed-torque characteristics of the motor involved to achieve a cutout speed for the starting winding sufficiently close to the operating speed of the motor so that ample torque is developed for start up under load before taking the starting winding out of the circuit, and yet a rapid build up to operating speed is achieved by not keeping the starting winding in the circuit unnecessarily long.

Ordinarily, the cut-out point is at a speed which is 70-80% of the synchronous speed of the electric motor involved, as this percentage of operating speed is very close to the point at which the torque developed by the main or running winding alone becomes equal to or greater than the torque developed by the combined starting and running windings. When cumulative manufacturing tolerances change the spacing between the centrifugal device 10 and the stationary switch 15 in either a plus or a minus direction, the cut-out speed at which the device 10 operates is affected to a considerable extent. Cumulative manufacturing tolerances of as little as 0.045 inches in one direction or the other can result in a difference of as much as 15 percentage points in the cut-out speed of the device, expressed as a percentage of the running or operating speed of the motor. For a fuller discussion of these factors, reference is made to my U.S. Pat. No. 2,768,260 which was directed to the alleviation of some of these problems by an improvement in the stationary switch to overcome and compensate for some of the variations in manufacturing tolerances.

As best seen in FIGS. 2-6, the device 10 includes a body 17, preferably made of molded synthetic resin of symmetrical shape, here shown as circular, and having a central opening 18 extending axially therethrough, to permit the device to be slidably mounted and secured on the shaft 12 of the electric motor or other rotary device for coaxial rotation therewith. The shaft mounted device represents one means for securing the device for coaxial rotation, it being understood that any other suitable form of securement could be utilized in any particular speed-control or speed-governing application, if shaft mounting is not feasible or desirable or if some other form or rotary member of a power train, other than a shaft, is to be monitored or controlled. It will also be understood that although the control device 10 is described in the environment of an electric motor for the control if its starting winding circuit, this is merely exemplary and that the control device can be utilized for other comparable circuits and mechanisms, which also may include visual or audible signal means, in addition to the control and monitoring functions herein described.

The body is provided with an open hollow cavity 19 defined by an annular forwardly-projecting side wall 20 within which is slidably received a disk-shaped conical spring 21 having a plurality of forwardly projecting integral resilient fingers 22. This conical spring is a constant-load spring which exerts a substantially uniform pressure over a relatively wide range of deflection, with the spring arms 22 serving as lever arms to cause snapaction of the ring portion 23 of the spring for both retraction and advancement of the shoe 13. The characteristics of this type of spring are more fully discussed and disclosed in my aforesaid U.S. Pat. Nos. 2,616,682 and 2,768,260.

The annular side wall 20 is provided with an internal annular sloping shoulder or ledge 24 which serves as an.

abutment or support for the ring portion 23 of the conical spring 21. By reason of the angular slope of the shoulder 24, the spring is supported only at its edge or periphery at the groove 25 formed at the intersection of the shoulder 24 and the side wall 20. This provides a form of knife-edge pivot for the pivotal movement of the ring portion 23 which results in substantially friction-free pivotal mounting of the spring 21. This arrangement also leaves the conical spring 21 free of any fixed securement to the body 17 and permits it to have a small extent of float in an axial direction.

The side wall 20 of the body 17 is provided with a plurality of axially-extending circumferentially-spaced cavities or recesses 26 which are open to the body cavity 19. The ring portion 23 of the conical spring 21 is provided with a plurality of circumferentially-spaced ears 27 which are provided with an aperture or opening 28 to accomodate a fastener element, preferably a rivet. A weight 16 is secured, as by rivet 29, to one of the ears 27 of the spring; the weight being accomodated or contained within one of the recesses 26 in close proximity to the opposed side walls 30 of the recess. In contrast to the structure of prior art devices of this type, it will be noted that the weights 16 are not connected in any manner to the body 17 of the device, but are directly riveted to the ears of the spring so that a flat upper surface 31 of the weight can be in direct underlying abutment with the riveted portion of the spring and provide a broad and solid base for the spring at that point to minimize the possibility of undue fatigue or fracture at the weakened spring section. It will also be noted that the prior art form of rivet stub, integral with the weight and rolled over onto the spring after traversing a damping grommet, has also been eliminated in favor of a solid rivet having a full head 32 whose large surface area can be brought into abutment with the spring to distribute stresses over a broader surface area of the spring. The previously used prior art damping grommet is no longer needed or utilized in this arrangement.

The shoe 13 is preferably provided with a diskshaped face 33 for engagement with the switch arm 14 or other control which is to be engaged thereby. The shoe is provided with a central aperture 34 to permit traversal thereof by the motor shaft 12. Extending rearwardly from the face or disk 33 of the shoe are a plurality of posts or legs 35 whose upper portion is grooved as at 36 to slidably receive and retain the hooked ends 37 of the spring fingers 22.

The side wall 20 of the body 17 is provided with an externally projecting shoulder or ledge 38 which provides a groove or recess to accomodate or receive a spring wire clip 39 whose inturned ends 40 resiliently engage the opposite side walls 30 in one of the recesses 26 and traverse the recess to overlie and engage the surface of the ring portion 23 of the conical spring. The clip 39 serves as a retainer to limit separating movement of the spring 21 from the body 17 of the device.

As thus described, the rotary centrifugal speedresponsive device will, through the leverage of the spring fingers 22 acting on the shoe 13, cause the shoe to be advanced or projected against the switch arm 14 to close the starting winding circuit when the device is in the non-rotating or static condition. In response to rotation, the weights 16 will be caused to swing in an outboard direction to cause deformation of the ring portion of the conical spring 21 by pivotal movement of the edge of the ring 23 about the fulcrum provided by the groove 25. The conical disk spring is preferably of the snap-action type so that as the weights 16 move progressively further in an outboard pivotal direction of movement, the ring portion 23 is sufficiently stressed and deformed to cause snap action retraction of the spring fingers 22 and consequent withdrawal of the shoe 13 from its circuit-closing engagement with the switch 15. When the motor is deenergized or otherwise slowed down, the weights tend to move inboard and, at a predetermined speed, snap action of the lever spring fingers 22 occurs to advance or project the shoe back into its circuit-closing engagement with the stationary switch.

In addition to the centrifugal forces affecting the weights 16 in causing outboard pivotal movement thereof, there is also a torsional force to which the weights are subjected which results from the rapid rates of orbital acceleration of presentday motors. These high acceleration rates tend to cause a torsional or orbital displacement of the weights in a circumferential direction which is undesirable as it introduces twists and stresses on the ring portion of the conical spring in a direction for which the spring is not designed and which only unnecessarily fatigue and distort the spring without serving any useful purpose. This excessive excursion of the weights in the circumferential or orbital direction is eliminated by the containment of the weights between the opposed side walls 30 of the recess during the centrifugal outboard movement of the weights. Thereby any tendency to excessive excursion of the weights in this direction is mechanically blocked by the walls 30, so that the effect of such movement and its fatiguing effect on the spring is eliminated.

The spring wire clip 39 may serve a dual function. It will be noted that the main or body portion 41 of the clip 39 extends across the recesses 26 in overlying relationship to the weights 16. Thus, in addition to providing a means for retaining theconical spring 21 in the body 17, the retainer clip 39 is also in a position to provide a physical abutment in the path of outboard centrifugally-induced pivotal movement of the weights 16 to arrest excessive excursion of the weights in this direction of movement. It will be apparent that as soon as the weights 16 have swung outwardly sufficiently to cause snap action withdrawal movement of the spring fingers 22 and the shoe 13, further outboard movement of the weights is operatively ineffective and merely causes unnecessary stress and fatigue on the ring portion of the conical spring 21. By providing a recessed surface 42 on the weight 16 in the area where it would engage the body of the retainer 39 and calibrating this configuration of the weight so that an arresting abutment occurs between the weight and the retainer 39 just beyond the point where the weight has attained a centrifugally-induced outboard position which is oepratively effective, further unnecessary centrifugallyinduced outboard movement of the weight is mechanically restrained by the body 41 of the retainer 39 so as to eliminate any unnecessary distortion and fatigue of the conical spring by the outboard movement of the weights at speeds above the cut-out speed of the device, as indicated in phantom outline in FIG. 5.

It will be noted that the peripheral knife-edge floating mounting of the conical spring 21 in the body 17 increases the lever arm of the spring fingers 22 so that sensitivity and response of the device is enhanced, contributing to more accurate calibration and control of the speed governing characteristics of the device.

As above mentioned, the described arrangement of parts results in the fexible and resilient spring fingers 22 acting as the sole support for the shoe 13 and results in a somewhat unstable condition of the shoe permitting it to tilt or wobble during rotation. Such tilting or wobbling of the shoe may be reflected in a condition of flutter in the stationary switch and will also result in undesired variations from the performance characteristics to which the device is designed. It has been found that the posture of the shoe l3 and of the fingers 22 can be stiffened or reinforced to create a more stable condition by a combination of two factors. The first of these is utilization of a stabilizer ring or plate 43 which underlies the ring portion 23 of the spring 21 and is secured to the shoe 13 on the underside thereof as by attachment to the legs 35 by means of any suitable fastener 44.

The stabilizer plate is provided with a central aperture 45 permitting traversal of the motor shaft 12 therethrough and is also provided with circumferentiallyspaced recesses or notches 46 which are complementary to the position and spacing of the recesses 26 in the body 17, as well as complementary to the correspondingly spaced cars 27 of the spring 21.

When the shoe 13 is advanced or projected by the spring fingers 22 to the limit of their movement, approaching the unstressed or untensioned condition of these fingers, the underlying stabilizer plate 43 is brought into abutment with the ring portion 23 of the disk spring to provide'a large surface area of support for the spring 21 around its entire periphery, to minimize the tilting or wobble above-mentioned. This arrangement results in a mechanical restriction resisting any tilting tendency or wobble of the shoe 13 by adding an element of stabilization to the shoe in addition to the support provided by the spring fingers. On retraction, the rearward axial displacement of the shoe is arrested by abutment of the legs 35 with a portion of the body 17.

This improvement in stability of the shoe achieved by utilization of the plate 43 can be further enhanced by establishing a predetermined spacing between the stabilizer plate 43 and the anchor points of the spring fingers 22 on the body 17 so as to achieve pretensioning of the fingers 22 by vertical displacement thereof to the extent of or more from their free or un-stressed posture. Thereby the fingers 22 are always maintained under a condition of tension to increase their stiffness and thus provide additional support stability to prevent wobble or tilting of the shoe 13. In the design of the device 10, this pre-tensioning of the spring fingers can be compensated for in the mass of the weights used to achieve the desired cut-out and cut-in speeds of the device.

Both the body 17 and the shoe 13 are preferably and conveniently formed of molded synthetic resin which can be produced to much closer manufacturing tolerances than comparable metal components which are production stampings. Through use of the stabilizer plate 43, the shoe 13, the spring 21 and the body 17 are capable of being asembled to have a fixed and predeinfluenced by the variations which might occur in the height of the spring fingers resulting from manufacturing tolerances. The greater precision of manufacturing tolerances in the molded plastic parts when combined with the adaptability of the device to being assembled in a predetermined maximum axial length, greatly minimizes speed-governing performance variations of the device which resulted from cumulations of manufacturing tolerances in the various components thereof. Additional benefits derived from this arrangement of the device are a greater rate of increase in spring resistance in moving toward the over-center position, as well as improved snap-action at the over-center position; greater versatiity and precision in establishing the cutout and cut-in points of the device; and less variation in predetermined operating characteristics.

' terined maximum axial length which no longer need be r It will be noted that although the body 17 is illustrated in the drawings as being provided with six equally spaced recesses 26 and there are likewise six securement ears 27 on the conical spring and six notches 46 in the stabilizer plate, all correspondingly spaced, there are only three weights'l6 shown, spaced 120 from each other. The device is adapted to accomodate either three or four or six weights 16, thus permitting versatilityindesign and assembly without any necessary change in the basic components.

In FIG. 7 of the drawings, there is shown a modified form of the invention in which the body 17a has integrated therewith and includes a molded plastic fan assembly 47 having a disk-shaped web 48 and projecting fan vanes or blades 49. The previously described improvements made in the device 10 permit its size and mass to be reduced significantly to a point where integration of a fan cooling assembly therewith becomes feasible.

The inner peripheral edge 50 of the web 48 is located in such position relatively to the recesses 26 as to provide a limiting abutment or retainer edge in the path of outboard movement of the weights 16 and thereby serves in the same manner as the previously described utilized if it is not desired to rely upon the separate retaining means provided by the spring wire clips 51 and the inner edge 50 of the web 48. The opposed side walls 30 of the recesses 26 still serve the purpose of preventing excessive excursion of the weights in an orbital direction, as previously described.

Having thus described my invention, I claim:

1. In a rotary centrifugal speed-responsive device for actuating a control element, the combination of an open-ended body adapted for securement to a rotatable member for coaxial rotation therewith, a plurality of circumferentially-spaced axially-extending recesses provided in said body, a disk-shaped conical spring slidably received in and peripherally supported by said body for knife-edge pivotal movement, said spring having a plurality of circumferentially-spaced weights operatively secured thereto and movably contained in said recesses in close proximity thereto to prevent torsionally-induced excursion thereof, a control-engaging shoe operatively connected to said spring radially inwardly of said weights and projected by said spring in the static position of said device and axially-retractable in response to weight-induced deformation of said spring to move said shoe toward and away from control-actuating position and retainer means carried by said body for limiting separating movement of said spring relatively to said body.

2. A combination as defined in claim 1, including second retainer means carried by said body in the path of centrifugallyeinduced outboard movement of said weights to limit said outboard movement thereof.

3. A combination as defined in claim 1, wherein said retainer means include portions disposed in the path of centrifugally-induced outboardmovement of said weights to limit said outboard movement thereof.

4. A combination as defined in claim 1, wherein said body presents an annular shoulder portion, and said retainer means is a clip seated in said shoulder portion and engaging said spring in overlying relationship.

5. A combination as defined in claim 1, wherein said body includes a plurality of outwardly-extending fan blades and said recesses are interposed between at least some adjacent pairs of fan blades.

6. A combination as defined in claim 1, wherein said conical disk spring is provided with a plurality of spirally-extending resilient fingers defining lever arms engaging said shoe, and the fulcrum of said lever arms is at the periphery of said spring.

7. A combination as defined in claim 1, wherein said spring has an over-center snap-action characteristic.

8. A combination as defined in claim 1, including a stabilizer plate secured to said shoe and underlying said spring whereby said shoe normally urges said stabilizer plate into supporting abutment with said spring.

9. In a rotary centrifugal speed-responsive device for actuating a control element, the combination of an open-ended body adapted for securement to a rotatable member for coaxial rotation therewith, a diskshaped conical spring slidably received in and peripherally supported by said body for knife-edge pivotal movement, said spring having a plurality of circumferentially-spaced weights operatively secured thereto, a control-engaging shoe operatively connected to said spring radially inwardly of said weights and projected by said spring in the static position of said device and axially-retractable in response to weight-induced deformation of said spring to move said shoe toward and away from control-actuating position, a stabiizer plate secured to said shoe in underlying relationship to said spring whereby said shoe normally urges said stabilizer plate into supporting abutment with said spring, and retainer means carried by said body for limiting separating movement of said spring relatively to said body.

10. A combination as defined in claim 9, wherein the spacing between said stabilizer plate and said shoe is predetermined to cause selective pre-tensioning of said spring in the static position of the device.

11. A combination as defined in claim 9, wherein said stabilizer plate is provided with a plurality of peripheral notches coincident with said plurality of weights.

12. A combination as defined in claim 9, including a plurality of legs projecting from said shoe and traversing said spring, and said stabilizer plate being secured to said legs.

13. A combination as defined in claim 9, wherein said stabilizer plate limits axial extension of said shoe.

14. A combination as defined in claim 9, wherein said body is provided with abutments disposed in the path of retractive axial displacement of said legs to limit spring-induced retractive displacement of said shoe.

15. In a rotary centrifugal speed-responsive device for actuating a control element, the combination of an open-ended body adapted for securement to a rotatable member for coaxial rotation therewith, a plurality of circumferentially-spaced axially-extending recesses provided in said body, a disk-shaped conical spring slidably received in and peripherally supported by said body for knife-edge pivotal movement, said spring having a plurality of circumferentially-spaced wieghts operatively secured thereto and extending into said recesses, said recesses having portions engageable with said weights to limit circumferential displacement thereof relatively to said body, a control-engaging shoe operatively connected to said spring and projected by said spring in the static position of said device and axially retractable in response to weight-induced deformation of said spring to move said shoe toward and away from control-actuating position, a stabilizer member secured to said shoe in underlying relationship to said spring whereby said shoe in static position urges said stabilizer member into supporting abutment with said spring, retainer means carried by said body in the path of centrifugally-induced displacement of said weights for limiting excessive excursion thereof, and second retainer means carried by said body for limiting separating movement of said spring relatively to said body.

16. A combination as defined in claim 15, wherein said body includes a plurality of outwardly-extending fan blades and said recesses are interposed between at least some adjacent pairs of fan blades.

17. A combination as defined in claim 16, wherein said first-named retainer means comprises an abutment of said recesses. 

1. In a rotary centrifugal speed-responsive device for actuating a control element, the combination of an open-ended body adapted for securement to a rotatable member for coaxial rotation therewith, a plurality of circumferentially-spaced axiallyextending recesses provided in said body, a disk-shaped conical spring slidably received in and peripherally supported by said body for knife-edge pivotal movement, said spring having a plurality of circumferentially-spaced weights operatively secured thereto and movably contained in said recesses in close proximity thereto to prevent torsionally-induced excursion thereof, a control-engaging shoe operatively connected to said spring radially inwardly of said weights and projected by said spring in the static position of said device and axially-retractable in response to weight-induced deformation of said spring to move said shoe toward and away from control-actuating position and retainer means carried by said body for limiting separating movement of said spring relatively to said body.
 2. A combination as defined in claim 1, including second retainer means carried by said body in the path of centrifugally-induced outboard movement of said weights to limit said outboard movement thereof.
 3. A combination as defined in claim 1, wherein said retainer means include portions disposed in the path of centrifugally-induced outboard movement of said weights to limit said outboard movement thereof.
 4. A combination as defined in claim 1, wherein said body presents an annular shoulder portion, and said retainer means is a clip seated in said shoulder portion and engaging said spring in overlying relationship.
 5. A combination as defined in claim 1, wherein said body includes a plurality of outwardly-extending fan blades and said recesses are interposed between at least some adjacent pairs of fan blades.
 6. A combination as defined in claim 1, wherein said conical disk spring is provided with a plurality of spirally-extending resilient fingers defining lever arms engaging said shoe, and the fulcrum of said lever arms is at the periphery of said spring.
 7. A combination as defined in claim 1, wherein said spring has an over-center snap-action characteristic.
 8. A combination as defined in claim 1, including a stabilizer plate secured to said shoe and underlying said spring whereby said shoe normally urges said stabilizer plate into supporting abutment with said spring.
 9. In a rotary centrifugal speed-responsive device for actuating a control element, the combination of an open-ended body adapted for securement to a rotatable member for coaxial rotation therewith, a disk-shaped conical spring slidably received in and peripherally supported by said body for knife-edge pivotal movement, said spring having a plurality of circumferentially-spaced weights operatively secured thereto, a control-engaging shoe operatively connected to said spring radially inwardly of said weights and projected by said spring in the static position of said device and axially-retractable in response to weight-induced deformation of said spring to move said shoe toward and away from control-actuating position, a stabiizer plate secured to said shoe in underlying relationship to said spring whereby said shoe normally urges said stabilizer plate into supporting abutment with said spring, and retainer means carried by said body for limiting separating movement of said spring relatively to said body.
 10. A combination as defined in claim 9, wherein the spacing between said stabilizer plate and said shoe is predetermined to cause selective pre-tensioning of said spring in the static position of the device.
 11. A combination as defined in claim 9, wherein said stabilizer plate is provided with a plurality of peripheral notches coincident with said plurality of weights.
 12. A combination as defined in claim 9, including a plurality of legs projecting from said shoe and traversing sAid spring, and said stabilizer plate being secured to said legs.
 13. A combination as defined in claim 9, wherein said stabilizer plate limits axial extension of said shoe.
 14. A combination as defined in claim 9, wherein said body is provided with abutments disposed in the path of retractive axial displacement of said legs to limit spring-induced retractive displacement of said shoe.
 15. In a rotary centrifugal speed-responsive device for actuating a control element, the combination of an open-ended body adapted for securement to a rotatable member for coaxial rotation therewith, a plurality of circumferentially-spaced axially-extending recesses provided in said body, a disk-shaped conical spring slidably received in and peripherally supported by said body for knife-edge pivotal movement, said spring having a plurality of circumferentially-spaced wieghts operatively secured thereto and extending into said recesses, said recesses having portions engageable with said weights to limit circumferential displacement thereof relatively to said body, a control-engaging shoe operatively connected to said spring and projected by said spring in the static position of said device and axially retractable in response to weight-induced deformation of said spring to move said shoe toward and away from control-actuating position, a stabilizer member secured to said shoe in underlying relationship to said spring whereby said shoe in static position urges said stabilizer member into supporting abutment with said spring, retainer means carried by said body in the path of centrifugally-induced displacement of said weights for limiting excessive excursion thereof, and second retainer means carried by said body for limiting separating movement of said spring relatively to said body.
 16. A combination as defined in claim 15, wherein said body includes a plurality of outwardly-extending fan blades and said recesses are interposed between at least some adjacent pairs of fan blades.
 17. A combination as defined in claim 16, wherein said first-named retainer means comprises an abutment of said recesses. 